1. Field of the Invention
The present invention pertains generally to a system of interlocking modular conduit spacers for holding banks of utility ducts or conduits in parallel spaced relationship, and more particularly to a component for attachment to the modular spacers for anchoring a utility duct bank in a fixed position in the bottom of a trench within which it is installed while it is being encased in concrete or otherwise buried in the earth.
2. Description of the Prior Art
Utility lines such as electric power lines and telephone lines which are to be laid underground are commonly installed within pipes or conduits buried beneath the earth's surface. The pipes or conduits are laid in trenches excavated in the earth, with the trenches then being backfilled with an appropriate material, generally earth or poured concrete, to firmly encase the pipes or conduits and permit loads to be carried thereover. It is desirable for the pipes or conduits to maintain a spaced parallel relationship and remain in a fixed position as they are buried or encased in concrete. To that end, the pipes or conduits are generally supported within the trench in banks or bundles by a supporting framework comprised of interconnected modular spacers as shown for example in U.S. Pat. No. 3,856,246. The pipes or conduits are thus maintained in the desired spatial relationship within the trench pending backfilling, and they maintain their spaced parallel positions with adequate space therebetween to permit the filling material or concrete to flow around and completely fill the space between the pipes or conduits as the trench is filled. As the filling material is initially placed in the trench it tends to displace or move the bank of pipes or conduits until sufficient material has been deposited to secure them in place. When the filling material is poured concrete an additional problem is encountered in that the relatively lightweight, hollow pipes or conduits tend to be buoyed upwardly or floated by the newly poured fluid concrete. A number of devices have been proposed to anchor the duct bank within the trench and insure that it will remain stationary and in the proper position within the trench while being buried or encased in concrete. Thus, some spacers have been provided with hollow corner posts through which vertical reinforcing bars are inserted and driven into the floor of the trench. The base or platform of the spacers of the aformentioned U.S. Pat. No. 3,856,246 is provided with holes through which a rod can similarly be inserted and driven into the ground in the floor of the trench. Still other devices for this purpose have included wooden or metal T's and forks engaged over portions of the spacers and driven into the floor of the trench.
None of the aforementioned devices has proven entirely satisfactory in anchoring a utility duct bank to the bottom of the trench so that it will remain in a fixed position while being encased in concrete or otherwise buried in the earth. Thus, the prior art devices do not provide the desired stability throughout the height of the duct bank nor permit flexibility in locating the devices at various positions where they may be needed. In some of the devices the metallic anchoring rods are positioned immediately adjacent the pipe or conduit so as to constitute objectionable electromagnetic interference with the high capacity conductors within the conduit.